The improvements described herein generalize the definition of QUS by adding:
(1) estimates based on variables of the statistics of the envelope of linearly amplified, radio-frequency ultrasound echo signals backscattered from biological or non-biological materials to
(2) estimates based on variables of normalized power spectra of linearly amplified, radio-frequency ultrasound echo signals in previously described QUS methods such as those shown in the '342 patent, and optionally
(3) one or more global variables such as clinical data, e.g., antigen level or patient age, when typing tissue or such as material properties, e.g., acoustic attenuation or mass density, when typing non-biological material.
The improvements also generalize the application of the covered QUS methods to any and all materials in which pulse-echo ultrasound produces echo signals within the material and where such echo signals result from spatial variations in the acoustical impedance of the material on a scale of fractions to multiples of the incident acoustical-pulse wavelength.
Although specific clinical examples are cited herein to illustrate applications of the described method, the method is applicable to a very broad range of material-typing and imaging applications in addition to the cited clinical, tissue-typing and imaging applications. Examples of potential non-biological material-typing and imaging applications include, but are not limited to, assessment of composite quality, fiber density in fiber-reinforced plastics, crystalline-material properties, particle size and concentration in liquid suspensions, etc. An example of a potential non-clinical, biological-material typing and imaging includes, but is not limited to, beef-quality grading. Examples of potential clinical applications include, but are not limited to, distinguishing among healing, non-healing and infected wounds; distinguishing between ischemic and non-ischemic myocardium; distinguishing among progressing, static, and regressing lesions; distinguishing between lesions that are responsive to treatment and those that are unresponsive to treatment; etc. Furthermore, in clinical applications, the method may be able to grade conditions such as, for example, the degree of treatment response, severity of ischemia, extent of infection, rate of healing, depth of burns, pressure or friction-ulcer status, progression of disease; etc.
For example, two salient, representative clinical applications are detection and imaging of cancer in the prostate gland or of metastases in lymph nodes. Reliable detection of primary-cancer foci in the prostate or metastatic foci in lymph nodes is critical for staging the disease and planning its treatment. The described method of cancer detection analyzes raw ultrasound echo-signal data in two- or three-dimensions (2D or 3D) in combination with global clinical variables such as serum PSA (prostate-specific antigen) values in the case of prostate cancer or primary-tumor type in the case of lymph-node metastases to generate 3D images that depict cancerous foci in the prostate or lymph nodes and thereby that reliably detect, characterize, and localize metastatic regions.
A reliable method using spectrum-analysis-based QUS to characterize and type biological tissue is described in the '342 patent and is incorporated herein by reference. The '342 patent describes a method that combines spectrum-analysis-based QUS variables (i.e., the slope, intercept, mid-band variables of the so-called normalized power spectrum and also the effective scatterer size and so-called acoustic concentration estimates that are derived from the spectral variables and known ultrasound-system properties) with global clinical data.
The improvements described herein additionally combine variable values of the envelope statistics of ultrasound echo signals derived from the tissue of interest with the spectrum-analysis-based variable values and global variables described in the '342 patent, and/or described herein.